Carnival Dream and Carnival Glory were the latest to resume operations at the weekend.
It brings the total number of Carnival vessels in service to 11, including new ship Mardi Gras.
The line has said more ships will return to service over the coming months and into 2022, operating from seven US homeports – Miami, Galveston, Seattle, Port Canaveral, Long Beach, Baltimore and New Orleans.
"Having half of our US fleet back in operations provides positive economic impact in our homeports and port of call destinations, along with giving our guests their much-needed vacations and helping our crew support their families back home," said Christine Duffy, president of Carnival Cruise Line.
"We couldn’t have accomplished this without the support of our travel advisor partners, business partners and port and destinations partners."
